a-a a-b a-c aaa aab aac aae aak aam aas ab- aba abb abc abe abk abm abs ac- aca acb acc ace ack acm acs aea aeb aec aee aek aem aes aka akb akc ake akk akm aks ama amb amc ame amk amm ams as- asa asb asc ase ask asm ass baa bab bac bae bak bam bas bba bbb bbc bbe bbk bbm bbs bca bcb bcc bce bck bcm bcs be- bea beb bec bee bek bem bes bka bkb bkc bke bkk bkm bks bma bmb bmc bme bmk bmm bms bsa bsb bsc bse bsk bsm bss c-- caa cab cac cae cak cam cas cba cbb cbc cbe cbk cbm cbs cca ccb ccc cce cck ccm ccs ce- cea ceb cec cee cek cem ces cka ckb ckc ckm cks cma cmb cmc cme cmk cmm cms csa csb csc cse csk csm css eaa eab eac eae eak eam eas eba ebb ebc ebe ebk ebm ebs ec- eca ecb ecc ece eck ecm ecs eea eeb eec eee eek eem ees eka ekb ekc eke eks em- ema emb emc eme emk emm ems es- esa esb esc ese esk esm ess ka- kaa kab kac kae kak kam kas kba kbb kbc kbe kbk kbm kbs kca kcb kcc kce kck kcm kcs ke- kea keb kec kee kek kem kes kkb kkc kke kkk kkm kks kma kmb kmc kme kmk kmm kms ksa ksb ksc kse ksk ksm kss maa mab mac mae mak mam mas mba mbb mbc mbe mbk mbm mbs mc- mca mcb mcc mce mck mcm mcs mea meb mec mee mek mem mes mka mkb mkc mke mkk mkm mks mma mmb mmc mme mmk mmm mms msa msb msc mse msk msm mss saa sab sac sae sak sam sas sba sbb sbc sbe sbk sbm sbs sca scb scc sce sck scm scs se- sea seb sec see sek sem ses sk- ska skb skc ske skk skm sks sma smb smc sme smk smm sms ss- ssa ssb ssc sse ssk ssm sss